A sub 400° C. ALD process for growing monolayers of Si on clean surfaces by alternating pulses of Si2H6 and SiCl4 employed with the substrate temperature varied between 355°-385° C. The process is slow, with each ALD cycle taking several minutes and the desorption of the HCl(g) byproduct being slow below 400° C. Other processes include monolayer silicon ALD growth on Ge with use of alternating pulses of Si2Cl6 and atomic hydrogen, or Si2Cl6 and Si2H6, at undesirably high substrate temperatures of 400°-465° C.
Physical vapor deposition (PVD) of silicon for passivation of III-V surfaces has been reported, but requires a silicon multilayer as the silicon is not ordered. Also, the PVD deposition of silicon is not compatible with processing of three dimensional devices such as finFETs on large semiconductor wafers.